This is a 2-center, randomized, controlled trial of the effect of Behavior Family System Therapy (BFT) on diabetic control and adherence in IDDM. Subjects with IDDM and high levels of family conflict (N=120 from two centers; N=60 from this center) will be recruited and randomly assigned to receive BFT, a non-behavioral education/support intervention, or no additional intervention (control) during a 3-month period, and evaluated four times over the next 15 months.